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There are very few "fundamental" laws - everything else is ultimately derived from them. But let's look at Maxwell's equations just to see how tricky your question really is. Maxwell's equations are usually considered "fundamental" but they arrived after Ampère's law and Faraday's law - both of which describe "engineering principles" (magnetic field due ...


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Light years help give an idea of distances through space and time. When we look at a star 100 light years away, that 100 light years not only gives an idea of the immense distance to the object but will also tell us that what we see is light from 100 years in the past.


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Ultimately, the answer boils down to convenience. When we want to describe the distance between here and, for instance, the star Sirius (the brightest star in our night sky), it would be a little cumbersome to write $\ell=8.13\times10^{18}\,{\rm cm}$ any time we want to write its distance from us. And really this goes for any astronomical object: they're ...


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Whenever you see things at a distance, your perceptions are of things that happened in the past. You can see it at a football game, for example, where someone kicking the ball is seen very much before it is heard (sound is slower than light). Light only has a finite speed, too; and light turns out to be the fastest thing there is. A light year is the ...


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Ballpark (based on the iron starting out at 0 degrees Kelvin and melting at 1538 and the earth's radius of about 6000000 meters and the mass of a fly about 12 milligrams and velocity of a fly about 2 meters per second) (EDIT: Also based on the assumption of no radiative cooling of the sphere, i.e., perfect transfer of fly-bumping into heating the sphere and ...


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the magnet heats the metal which then melts the ice and makes it look like its glowing red hot.



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